1. Field of the Invention
The present invention relates to a compact, lightweight, self-contained rappel apparatus by which a person such as a parachuting smoke jumper, aviator, or other person may safely descend a line or rope from a tree canopy or other high perch to the ground or a lower elevation. The invention can also serve as a useful means of escape for a person from an upper floor of a building or other structure when the normal means of egress are blocked by fire or other hazardous condition.
2. Description of Related Art
A number of devices exist that can aid a person in descending or rappeling down a line to a lower elevation and in particular in descending from a tree canopy environment. In U.S. Pat. No. 4,102,431 issued to Carroll is disclosed a complex emergency personnel lowering apparatus for use with an accompanying lowering line for carriage and use by an aircrewman. In U.S. Pat. No. 3,419,236 issued to Weber, the problem of rescuing aircrewmen from high trees is also addressed. The prior devices are generally more cumbersome, bulky, and complex than the present invention. The present invention provides for a less complex descender that preferably uses a small diameter, high strength aramid kernmantle fiber line such as 3 mm Technora.RTM. cordage.
Generally prior art rappeling devices have utilized friction between the line and the device to slow descent by generating heat primarily in the structure of the device. The present invention permits a novel reeving of the line onto the invention resulting in multiple frictional line-to-line contact points as the line crosses itself. The line-to-line contacts result in a portion of the heat generated by braking to be imparted into the line directly and not directly into the structure of the descender. The invention thus is able to operate without building up as much heat in the structure of the descender as it would without the line-to-line contacts.